diff --git a/Core/include/Acts/Clusterization/Clusterization.hpp b/Core/include/Acts/Clusterization/Clusterization.hpp
index 5d4b6ad1461..39a1dc9b656 100644
--- a/Core/include/Acts/Clusterization/Clusterization.hpp
+++ b/Core/include/Acts/Clusterization/Clusterization.hpp
@@ -29,8 +29,8 @@ enum class ConnectResult {
 // Default connection type for 2-D grids: 4- or 8-cell connectivity
 template <typename Cell>
 struct Connect2D {
-  bool conn8{true};
-  Connect2D() = default;
+  bool conn8;
+  Connect2D() : conn8{true} {}
   explicit Connect2D(bool commonCorner) : conn8{commonCorner} {}
   ConnectResult operator()(const Cell& ref, const Cell& iter) const;
 };